Validity, Reliability and Reproducibility of the “Extended GRBAS Scale,” A Comprehensive Perceptual Evaluation of Dysphonia

Summary: Objective. To validate the Extended GRBAS Scale (GS) and to investigate its inter- and intra-rater reliability and reproducibility. The Extended GS contains the Standard GS with 8 added perceptual parameters similar to those present in the CAPE-V. Methods. We have carried out a retrospective study on 480 evaluation forms for the perceptual evaluation of dys- phonia with the Extended GS, examined by four experienced raters, 240 evaluations on running speech and 240 on sustained vowel /a/. The four raters examined, random and blind, 90 audio files of pathologic voices and 30 samples of normal voices. The pathologic samples were the pre- and post-phono surgery voices of 15 selected patients. The 30 pre-operative voice samples (15 of running speech and 15 of sustained vowel) were blindly re-assessed in a differ- ent order. Each rater annotated the difficulty in rating the added perceptual parameter and its “importance” for the assessment of dysphonia in that patient. Voices were recorded in standard conditions. All audio files were analyzed by the CSL and by the PRAAT, for an acoustic objective evaluation of meanF0 of conversational voice, Jitter%, Shimmer%, NHR, CPPS; we also verified the presence of sub-harmonics and undulation of F0 in the spectrogram. Results. The Extended GS showed good inter- and intra-rater reliability and reproducibility. It provided a more complete assessment than the Standard GS for documenting voice changes after Phono surgery. The 8 added per- ceptual parameters were judged “Slightly Important” in 34.4% of the samples, “Very Important” in 32.5% of the samples, “Not Difficult” in 80.4% of the samples. Significant correlations were found between perceptual evalua- tion with the Extended GS and acoustic analysis. Conclusions. The Extended GS is a useful tool for the voice clinician, who can use the Standard GS, or the Reduced GS (GRB) for a basic evaluation. The Extended GS provides for a comprehensive perceptual evaluation of dysphonia pre and post treatment.